Silver breeding bitch

I may be in the market for a silver breeding bitch. I would prefer one with Thinker in the background somewhere, but definately want one with a fantastic background health wise. This is a tiny seed in my brain, but I cannot imagine being without one now, and with Thinker being twelve, it is inevitable that it is going to happen at some point in the not too distant future. I would be looking at owning outright, but would consider co-ownership. any ideas???